1. Field of the Invention
The present invention generally relates to instruments and the like. More particularly, an embodiment of the invention relates to a bone probing device for examining holes drilled in bones to accommodate spinal implant fixation components.
2. Description of the Related Art
Spinal fixation, such as lumbar sacral fusion and the correction of spinal deformities such as scoliotic curves, is a well known and frequently used medical procedure. Pedicle, lateral, and oblique mounting devices may be used to secure corrective spinal instrumentation to a portion of the spine that has been selected to be fused by arthrodesis.
A spinal fixation system typically includes corrective spinal instrumentation that is attached to selected vertebrae of the spine by screws, hooks, and clamps. The corrective spinal instrumentation includes spinal rods or plates that are generally parallel to the patient's back. The corrective spinal instrumentation may also include transverse connecting rods that extend between neighboring spinal rods. Spinal fixation systems are used to correct problems in the lumbar and thoracic portions of the spine, and are often installed posterior to the spine on opposite sides of the spinous process and adjacent to the transverse process.
Various types of screws, hooks, and clamps have been used for attaching corrective spinal instrumentation to selected portions of the patient's spine. Examples of pedicle screws and other types of attachments are illustrated in U.S. Pat. Nos. 4,763,644; 4,805,602; 4,887,596; 4,950,269; and 5,129,388. U.S. patent application entitled "Polyaxial Spinal Fixation System and Method" having Michael C. Dinsdale and Erik J. Wagner as inventors and filed May 27, 1997 and U.S. patent application Ser. No. 08/740,123 filed Oct. 24, 1996 each relate to fixation of the human spine using pedicle screws and are incorporated by reference as if fully set forth herein.
Before a spinal implant can be attached to the spine with a pedicle screw, an opening is typically drilled into the spine to accommodate the screw. After the opening is drilled into the spine, it may be desired to determine whether drilling of the opening resulted in any cracks or openings in the interior side wall of the opening. The surgeon's field of view within such an opening tends to be limited. It is generally not possible to thoroughly examine the side wall for cracks or openings visually. Therefore, surgeons have used a pedicle probe to feel the interior side wall of the opening to locate any cracks or openings in the side wall. If it is determined that a crack or opening is present in the side wall, a new opening will typically be drilled in a different location to accommodate the screw.
After an opening has been drilled and found to be adequate upon inspection with a pedicle probe, a depth gage is typically inserted within the opening to determine its depth. Once the depth of the opening is determined, a screw having an appropriate length can be selected for insertion within the opening.
U.S. Pat. No. 5,242,448 to Pettine et al. relates to an orthopedic bone probing device to locate cavities, holes, and crevices in bones. The probing device includes "a cannula containing a shaft of superelastic material that assumes a retractable position angular to the axis of the cannula upon being ejected from one end of the cannula." See abstract. The "pre-conditioned `J` shaped shaft" may return to the "J" shape when it is extended beyond the tip of the cannula. Surgeons have experienced difficulty inserting conventional rigid rods having a curve or hook at the end into bone holes having a relatively small diameter. Pettine et al.'488 states "the value of the retractable probe is its ability to be inserted into small openings in the bone and then be extended out to serve as a useful bone probe." See Background and Summary of the Invention.